Extremely slow while compiling pulldown-cmark with RUSTFLAGS="-Zpolonius"

[Neutron3529]

I tried this code:

$ cargo clean && RUSTFLAGS="-Zpolonius" cargo check --timings && mv target/cargo-timings/cargo-timing.html ./cargo-timing-polonius.html

I expected to see this happen: The check finishes in several seconds

Instead, this happened: The check finishes after 10 minutes.

Meta

rustc --version --verbose:

rustc 1.87.0-nightly (f4a216d28 2025-03-02)
binary: rustc
commit-hash: f4a216d28ee635afce685b4206e713579f66e130
commit-date: 2025-03-02
host: x86_64-unknown-linux-gnu
release: 1.87.0-nightly
LLVM version: 20.1.0

Details

issue #75858 already said something about a slow compile with `-Zpolonius`, but such problem might not be solved (at least there's still some code that needs several minutes to compile with polonius.)

I've create a PR in rust-lang/polonius, but it seems that crate has been inactive for long. Thus I re-submit this PR here.

[Neutron3529]

@rustbot label I-slow NLL-polonius NLL-performant T-compiler

[amandasystems]

That would use the essentially abandoned Datalog backend for Polonius, which is known to be very slow. You might want to try -Z polonius=next, but that's also in development way before the "make it fast" step, and it's still very slow too. In fact, it's not even fully correct yet (since it's in development).

[lqd]

We also don't need both this issue and rust-lang/polonius#199. (As Amanda said, we're still working on -Zpolonius=next but it completes in 40s here)

[jieyouxu]

EDIT: nvm

[lqd]

Actually you’re right @jieyouxu, we can close in favor of the other issue. We don’t need to track this here, as we will not work on improving the datalog implementation from the other repo.

Thanks for opening an issue, we’ll keep the necessary discussion in a single place there.